Need opinions

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PlumCrazyJay

PlumCrazyJay

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I recently bought a 1991 360 out of a 3/4 ton pickup. Only 51,000 miles and I listened to it run before buying. Seemed to purr!!! Now the question. What could I expect for horsepower with a cast iron 340 intake and a 800cfm thermo-quad installed and not changing the cam? I need a lower rpm high torque output because of my highway gears (2.96 SG, 8 1/4) and tall tires. Also this is a 1970 Swinger that is used mostly on the highway but I want some go power between stop lights. I'm used to a 318 with a 4 bbl. intake and the TQ. I do have dual exhaust, 904 trans., factory AC. Second question. If I had a cam custom ground for my setup how much HP would I gain? I'm just looking for some round numbers. I'm still from the old school thought of " if it ain't broke don't fix it!" I'm weighing all my options before I do this "winter project". Thank you in advance for any info that might help me.
 
Probably 275hp or so stockish, and 325ish with 400 foot lbs at 3,500 RPMs with the right cam.
What you are asking from yours is almost exactly what I wanted out of mine and to keep freeway gears.
RustyRatRod (Rob) helped me when I asked almost that exact question.
I went on Youtube and looked up videos with different cams and found one I liked the sound of.
Then I looked at the duration and lobe separation for torque and sound, and considered my available lift limitations.
Got a custom grind from Oregon Cam Grinders for right at 150 shipped and mine is a Magnum cam (usually hundreds more) as I see Mag cams for 325-350 normally.
With a stock bottom 5.9 (360) with 9:1 compression, and Edelbrock 600, Edelbrock dual plane intake and 1 5/8 tube headers I got right about 350+hp and a little over 400 lbs of torque at 3,500 RPM's

I cheated and went a bit farther with it and added a 5 speed automatic out of a 1995 Dodge Dakota, so it not only gave me the lower first gear but 5 speeds total.
It now does 1,800 RPM's at 80mph on the freeway. (our speed limit is 75 on the freeways) but everyone does 85-90 on average.
Have I got a surprise for them. :D
 
The 91 360 should have 308 heads but, the exhaust valves have rotators. Intake and exhaust springs have different installed height and it doesn't take much to get into coil bind using rotators. Lunati and others grind cams for these TBI roller motors that may not need upgraded springs. You should ask them before buying a cam.
As is with the TQ you would have around 300hp flywheel and enough torque to melt the tires at will.
For a highway cruiser I would leave it as is.
 
mderoy340 said:
The 91 360 should have 308 heads but, the exhaust valves have rotators. Intake and exhaust springs have different installed height and it doesn't take much to get into coil bind using rotators. Lunati and others grind cams for these TBI roller motors that may not need upgraded springs. You should ask them before buying a cam.
As is with the TQ you would have around 300hp flywheel and enough torque to melt the tires at will.
For a highway cruiser I would leave it as is.
Click to expand...
Any thoughts as to gas mileage leaving the stock cam in and not making the TQ howl too many times?
 
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